warning C4189 (appVeyor)

[cvvergara]

On AppVeyor:

bool d = delete_obj();
assert(d && "delete failed with SEH disabled: runtime bug?");

c:\projects\geos\tests\unit\tut\tut.hpp(238): warning C4189: 'd': local variable is initialized but not referenced (compiling source file C:\projects\geos\tests\unit\capi\GEOSVoronoiDiagramTest.cpp) [C:\projects\geos\tests\unit\test_geos_unit.vcxproj]

Which means that the assertions are not processed.

But not such warning occurs when processing on Travis, which means that the assertions are being processed.

Possible solutions: 1) where needed:

::geos::ignore_unused_variable_warning(d);

2) on appveyor.yml

configuration: Debug

[Daniel Baston <dbaston@…>]

In 2cd5f5b/git:

Attempt to quiet TUT warnings in both MSVC, gcc

Fixes #904